An image forming method using a light-sensitive material which contains silver halide, a reducing agent and a polymerizable compound is disclosed Japanese Patent Publication No. 45(1970)-11149 (corresponding to U.S. Pat. No. 3,697,275, German Patent No. 1720665 and British Patent No. 1131200). The method comprises the steps of imagewise exposing to light the light-sensitive material and developing the material by a developing solution to imagewise harden the polymerizable compound so as to form a polymer image. In the method, the polymerization is caused by a radical of an oxidation product of the reducing agent, which is formed by the development of the silver halide.
On the other hand, another image forming method which employs a dry development process is disclosed in Japanese Patent Publication No. 61(1986)-69062 or No. 61(1986)-73145 (the contents of these two publications are described in U.S. Pat. No. 4,629,676 and European Patent Provisional Publication No. 0174634A). The method comprises imagewise exposing a light-sensitive material and heating the material to imagewise polymerize the polymerizable compound so as to form a polymer image. Further, Japanese Patent Provisional Publication No. 64(1989)-17047 (corresponding to U.S. Pat. No. 4,985,339) discloses a light-sensitive material which is heat-developable and is advantageously used in preparation of a printing plate.
In the above-mentioned image forming methods, silver halide, a reducing agent and a polymerizable compound are essential components. Further, a component having a function of accelerating image formation such as a base, a base precursor and a heat development accelerator has been preferably used.
So far these image forming functional components have usually been contained in a single layer (light-sensitive layer). In other words, the image forming functional components are scarcely separated into two layers. The following three embodiments (A), (B) and (C) are all the known multi-layered embodiments.
(A) One embodiment is a light-sensitive material wherein silver halide is separated from a polymerizable compound, which is disclosed in Japanese Patent Provisional Publication No. 58(1983)-121031 (corresponding to U.S. Pat. No. 4,547,450 and German Patent Provisional Publication No. 3300817A).
FIG. 9-A is a sectional view schematically illustrating the light-sensitive material disclosed in Japanese Patent Provisional Publication No. 58(1983)-121031. As is shown in FIG. 9-A, the light-sensitive material comprises a support (101), a polymerizable layer (102) containing the polymerizable compound and a light-sensitive layer (103) (silver halide photographic emulsion layer) containing the silver halide (.quadrature.) in the order. The reducing agent may be contained in the light-sensitive material. However, the reducing agent is usually contained in a developing solution, since the image forming method disclosed in Japanese Patent Provisional Publication No. 58(1983)-121031 employs a wet development process.
In the light-sensitive material separately having a light-sensitive layer and a polymerizable layer, it is essential for image formation that the radical of the oxidized reducing agent can be transferred from the light-sensitive layer to the polymerizable layer. As is described in Japanese Patent Provisional Publication No. 58(1983)-121031 (at column 2, lines 46-53 in U.S. Pat. No. 4,547,450), considering the instability of radicals, it is surprising that a radical formed in the light-sensitive layer diffused into another layer to initiate polymerization.
The image forming method disclosed in Japanese Patent Provisional Publication No. 58(1983)-121031 employs a wet development process using a developing solution, as is mentioned above. Accordingly, the developing solution permeates the light-sensitive layer and the polymerizable layer at the development process. Further, the reducing agents disclosed in the publication are soluble in water. Therefore, the radical of the oxidized reducing agent formed in the light-sensitive layer is transferred to the polymerizable layer with the developing solution. In other words, water contained in the developing solution functions as a medium or carrier of the radical.
As is mentioned above, the wet development process is the major promise of the separation in the disclosure of Japanese Patent Provisional Publication No. 58(1983)-21031.
(B) In the dry and heat development process, the applicant has noted that a reducing agent itself can be transferred between two layers. Therefore, the applicant has proposed a light-sensitive material wherein silver halide is separated from a polymerizable compound so long as the reducing agent itself functions as a polymerization inhibitor in an image forming method, as is disclosed in FIG. 2 of Japanese Patent Provisional Publication No. 61(1986)-75342 (which corresponds to FIG. 2 of U.S. Pat. No. 4,649,098).
FIG. 9-B is a sectional view schematically illustrating the light-sensitive material disclosed in Japanese Patent Provisional Publication No. 61(1986)-75342. As is shown in FIG. 9-B, the light-sensitive material comprises a support (111), a light-sensitive layer (112) containing silver halide (.quadrature.) and a reducing agent ( ) having the above-mentioned specific function and a photopolymerizable layer (113) containing a polymerizable compound and a photopolymerization initiator ( ) in the order.
But, the radical of the oxidized reducing agent is much less stable than the reducing agent itself as is described in Japanese Patent Provisional Publication No. 58(1983)-121031. Accordingly, it has not yet been considered nor tried at all to transfer the radical by heat between two layers.
(C) Japanese Patent Provisional Publication No. 62(1987)-253140 (corresponding to U.S. Pat. No. 4,797,343) discloses a light-sensitive material wherein a base or base precursor is contained in a layer different from the light-sensitive layer. A barrier layer is preferably provided between the light-sensitive layer and the layer containing the base or base precursor. The barrier layer keeps the base or base precursor from the light-sensitive layer, and when heated allows transmission of the base or base precursor. Accordingly, the barrier layer is not the image forming functional layer.
FIG. 9-C is a sectional view schematically illustrating the light-sensitive material (having the barrier layer) disclosed in Japanese Patent Provisional Publication No. 61(1986)-75342. As is shown in FIG. 9-C, the light-sensitive material comprises a support (121), a light-sensitive layer (122) containing silver halide (.quadrature.), a reducing agent (.DELTA.), a barrier layer (123) having the above-mentioned function and a layer (124) containing a base or base precursor (.gradient.) in the order.
The light-sensitive material disclosed in Japanese Patent Provisional Publication No. 61(1986)-75342 is based on the discovery that the base or base precursor can be transferred between two layers. The separated component was limited to the base or base precursor, since it was not discovered that the components other than the base or base precursor can be transferred between two layers.
The known multi-layered light-sensitive materials are limited to the above-described embodiments (A), (B) and (C) for the following reasons (1) and (2).
(1) In order to separate an image forming functional component of the light-sensitive material, the component must be transferred between two layers at a development process. It was discovered that a few components can be transferred between two layers, as is mentioned above. But, most of the components were indefinite with respect to the transference.
(2) The multi-layered light-sensitive material has a disadvantage that the process for preparation of the material is rather complicated. Accordingly, the multi-layered light-sensitive material is of no value without an advantage which can compensate the disadvantage. The advantage is merely found in the above-described three embodiments.
For the same reasons as mentioned above, a light-sensitive material having three or more image forming functional layers have not yet been proposed at all.